This invention relates to a composition of and a process for manufacturing a cross-linked ethylenic polymer foam structure having enhanced processability and physical properties.
Commercially-available, cross-linked ethylenic polymer foam structures (XLPE) are typically made with conventional low density polyethylene (LDPE) resins made by high pressure processes. LDPE resins have found favor because of their relatively low melt temperatures and desirable processability.
It would be desirable to have an XLPE foam structure with enhanced strength and resiliency, yet retain the low foam density and desirable resin processability afforded by the use of LDPE resins. One means of enhancing strength and resiliency is to employ a conventional linear low density polyethylene (LLDPE), a copolymer of ethylene and a C.sub.4 -C.sub.10 alpha-olefin. Unfortunately, LLDPE resin is difficult to process and to a XLPE foam, and results in a relatively high density foam structure with poor quality. It would be desirable to have an XLPE foam structure similar in strength and resiliency to an XLPE foam structure of LLDPE while comprising a resin having in an uncross-linked state processability similar to an LDPE resin.